Rotary compressor



D. C. RINEHART ROTARY COMPRESSOR Filed March 18, 1969 INVENTOR. DEAN C. R) NEHART United States Patent Olfice 3,532,448 ROTARY COMPRESSOR Dean C. Rinehart, Louisville, Ky., assignor to General Electric Company, a corporation of New York Filed Mar. 18, 1969, Ser. No. 808,133 .Int. Cl. F04c 23/02, 17/00 US. Cl. 418-63 7 Claims ABSTRACT OF THE DISCLOSURE A rotary compressor comprising a cylinder and a vane slidably mounted in the cylindrical wall of the cylinder includes a spiral spring for biasing the vane into engagement with the rotor. The spring has an inner end supported on an exterior hub portion of the compressor and spirals one revolution about the hub to engagement with the vane.

BACKGROUND OF THE INVENTION A known type of rotary compressor comprises a cylindrical wall defining a compression chamber, a rotor or roller eccentrically mounted within the cylinder and a vane slidably mounted in the cylindrical wall for continuout engagement of the inner end thereof with the periphery of the motor to divide the cylinder to a high pressure side and a low pressure side. To maintain the vane in continuous sealing engagement with the rotor surface, there is normally employed one or more compression springs positioned between the outer end of the vane and a suitable fixed base or support means. Such springs have been satisfactory for smaller compressors in which the vane moves a relatively short distance in maintaining contact with the rotor. However with the higher displacement rotor compressors in which the vane must move through a longer stroke during each rotation of the rotor, the vane springs must also be longer. Unless additional space is provided for these springs thereby increasing the size of the compressor, the safe stress limits of the springs may be exceeded with resultant spring breakage.

As a solution of this problem, it has been proposed, as described in Pat. 3,423,013 Rinehart issued 1 an. 21, 1969, to bias the vane into contact with the rotor by means including a plunger extending through the cylinder wall diametrically opposite the vane and a spring yoke engaging the outer ends of both the vane and the plunger for biasing both of these elements into engagement with the rotor in all positions of the rotor. This construction adds to the cost of the compressr in requiring the provision of the additional plunger element and the maintenance of sealing tolerances between the plunger and the opening in which it rides.

The present invention is directed particularly to the provision of a rotary compressor including vane biasing means consisting of a single vane spring exterior of the compressor wall structure having a shape or configuration such that substantially all the spring forces applied to vane are in line with its path of reciprocating movement.

In accordance with the illustrated embodiment of the invention, the rotary compressor comprises the usual cylindrical and end walls defining a compression cylinder, a rotor eccentrically rotatable within the cylinder and a radial slot in the cylindrical wall which slidably receives a radially extending vane having an inner end continuously engaging the periphery of the rotor to divide the compression cylinder into high and low pressure sides. One of the end wall members includes an axial projection on the outer surface thereof having an annular slot therein. The vane is maintained in engagement with the rotor by means of a spiral spring including an annular inner Patented Oct. 6, 1970 BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing:

FIG. 1 is an elevational view partly in cross section, of a portion of a hermetic refrigerant compressor incorporating the present invention; and

FIG. 2 is a sectional view along line 22 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the accompanying drawing, there is shown a hermetic compressor casing 1 in which there is disposed a rotary compressor unit 2 connected by a drive shaft 3 to an electric motor 4. The compressor 2 includes a cylindrical wall 6 having an inner cylindrical surface which, in combination with the upper and lower end walls or plates 7 and 8 defines an annular compression chamber 10. A rotor 11 driven by an eccentric 12 on the shaft 3 is contained within the cylinder 10. A vane 14 slidably disposed within a radial slot 15 extending through the cylinder wall 6 is adapted to engage the periphery of rotor 11 and divide the cylinder into a low pressure side 16 and a high pressure side 17.

The upper and lower end plates or walls 7 and 8 also have projections or hub portions 18 and 19 on the outer surfaces thereof respectively including upper and lower bearing surfaces 20 and 21 for the shaft 3.

Such a hermetic compressor is particularly adapted to be connected into a refrigeration system so as to withdraw low pressure or gaseous refrfigerant from the system through a suction line 22 having an outlet port 23 communicating with the low pressure side 16 of the compression chamber through valve 24 and to discharge high pressure refrigerant through a valved controlled discharge port 25 to the interior of the casing 1.

In order to prevent leakage of high pressure refrigerant from the high side 17 to the low side 16 during rotation of the rotor 12 in a clockwise direction as viewed in FIG. 2, it is necessary that the forward edge 26 of the vane 14 be maintained in continuous sealing engagement with the periphery of the rotor regardless of the position of the rotating rotorwithin the cylinder 10. This requires that during each rotationof the rotor, the vane must reciprocate between a forward position in which the vane extends into the cylinder as illustrated in the drawing and a retracted position in which the forward edge of the vane is substantially flush with the cylindrical compressor wall.

In accordance with the present invention, there is provided an improved means for biasing the vane into engagement with the rotor which does not require the provision of space within the wall structure defining the compressor cylinder and which does not require the provision of a plunger such as described in the aforementioned Pat. 3,423,013 Rinehart for assuring the application of longitudinal biasing forces to the vane. This vane biasing means comprises a spiral spring 30 positioned beneath or on the lower side of the compressor structure. This spring comprises an inner end portion 31 in the form of a substantially annular loop resiliently disposed in a circumferential slot 32 on the projection or hub portion 19 forming part of the lower end of plate 8'. A free intermediate portion of the spring generally indicated by the numeral 33 has a length of approximately 360 or in other words is in the form of a single loop extending from contact with the projection 19 at the point A in substantial radial alignment with the vane 14 to a point C below the outer end of the vane 14. This free intermediate portion 33 of the spring is disposed in a horizontal plane, that is in a plane perpendicular to the axis of the shaft 3 and rotor 12 and parallel to the path of travel of the vane 14. The outer end of the spring comprises an upwardly extending arm or portion 34 and an arcuate tip 36 received in an arcuate slot 37 in the outer end of vane 14 intermediate the upper and lower edges thereof.

The free intermediate portion of the spring is shaped so as to apply a substantially longitudinal bias to the vane 14 in all positions of the vane during operation of the compressor with a minimum lateral or side thrust. To this end, this free intermediate portion is spiralled outwardly at a gradually increasing radius from the point A to a point B which is about 180 from the point A or in other words on the diametrically opposite side of the shaft 3 from the point A. The remaining half of the free intermediate portion of the spring extending from the point B to the point C at which the spring is formed to provide the upwardly extending end portion 34 is of a substantially constant radius.

During operation of the compressor, the spring 30 flexes from its most contracted form illustrated in FIG. 2 of the drawing in which the vane 14 is in its innermost position to its most expanded form when the eccentric 12 is rotated through 180 and the vane 14 is in its outermost position. The flexing of the free intermediate portion 30 of the spring during this period involves two counterbalancing or counteracting actions. Point B moves towards the center line of the shaft 3 or in other words in the same direction as the vane 14- moves. There is thus a sharpening of the curve of the portion 33 between point A and B with a slight movement of point B and portion B-C in a clockwise direction as viewed in FIG. 2. Both of these movements are offset by proportional straightening of the portion of the spring between point B and point C which results in a counterclockwise movement of point C insofar as the action of spring segment B-C is concerned. These opposite flexing actions of the two portions of the spring generally offset one another so that point C is actually moved linearly in line with vane 14 thereby preventing any change in the direction of application of the spring force by end 36 on the vane 14. In other words, during operation of the compressor, substantially all of the spring force on the vane 14 is at all times longitudinal of the vane and in line with its reciprocating movement. It will be obvious of course that during reverse travel of the vane the vane is a sharpening of the curved portion BC of the spring and a lengthening or straightening of the portion of the spring from point A to C.

While the anchoring loop portion 31 of the spring extending about the projection 19 may be rigidly secured to the projection 19, it is preferably formed to provide only a gripping action on the projection 19 or in other words to permit rotation of the anchoring loop 31 about the projection 19 to facilitate the desired positioning of the spring relative to the vane 14. In other words, with this end of the spring free to rotate about the projection 19, the spring is free to assume its desired operating position relative to the vane 14 with no significant lateral forces on the vane. It will be appreciated of course that, from spring to spring, point A may not be in exact alignment with the vane 14 but it will always be on the same side of the projection 19 as the vane.

While it has been shown and described this specific embodiment of the present invention it will be understood that it is not limited thereto and it is intended by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by the Letters Patent of the United States is:

1. In a rotary compressor comprising a cylindrical wall and end walls defining a cylinder, a rotor eccentrial- 1y rotatable within said cylinder, said cylindrical wall having a radial slot therein, a vane slidably mounted in said slot for engagement with the periphery of said rotor, one of said end walls including a projection on the exterior surface thereof; means for maintaining said vane in engagement with said rotor comprising:

a spiral spring including an inner end supported on said projection, an outer end portion formed to engage said vane for biasing said vane into engagement with said rotor, and a free intermediate portion having a length of about 360 and extending from engagement with said projection at a point on the same side of said projection as said vane to a point aligned with the outer end of said vane.

2. The compressor claim 1 in which a first section comprising about of said free, intermediate spring portion gradually increases in radius from the point of engagement with said projection and the remaining 180 section is of substantially constant radius.

3. The compressor of claim 2 in which the plane of said free intermediate portion is perpendicular to the axis of rotation of said rotor.

4. In a rotary compressor comprising a cylindrical wall and end walls defining a cylinder, a rotor eccentrically rotatable Within said cylinder, said cylindrical wall having a radial slot therein, a vane slidably mounted in said slot for engagement with the periphery of said rotor, one of said end walls including a cylindrical projection on the exterior surface thereof coaxial with said cylinder and having a circumferential slot therein; means for maintaining said Wine in engagement with said rotor comprisa spiral spring including an annular inner end disposed in said slot, an outer end portion formed to engage said vane for biasing said vane into engagement with said rotor, and a free intermediate portion having a length of about 360 and extending from engagement with said projection at a point on the same side of said projection as said vane to a point in line with the outer end of said vane.

5. The compressor of claim 4 in which said free intermediate portion of said spring is in a plane parallel to the path of travel of said vane.

6. The compressor of claim 4 in which said free intermediate portion spirals outwardly from said projection for about 180 and thereafter has a substantially constant radius.

7. The compressor claim 6 in which said outer end portion of said spring engages the outer end of said vane at a point midway between its upper and lower edges.

References Cited UNITED STATES PATENTS 75,117 3/1868 Boicourt et al. 4l8248 600,753 3/1898 Tuttle 418--248 723,226 3/ 1903 Anderson 418248 2,023,608 12/1935 'Nebel 103123 2,134,936 11/1938 Getchell et al 230-139 2,898,032 8/1959 Katzenberger 230139 3,423,013 1/1969 Rinehart 230-139 FOREIGN PATENTS 1,100,191 3/1955 France.

HENRY F. RADUAZO, Primary Examiner US. Cl. X.R. 

